Till in error mode?

Start by actually working out what the make and model is. Search Gooogle for the manual
Search Gooogle for - say - the ' "model" displays C ' (replacing "Model" with your own data - that may throw up something.
If all else fails, come back here and re-post with enough info for people to have a stab at.
You may also find dedicated till forums, which may be more productive.

hterwe
October 2017